Printing is commonly performed in an ink-jet printer using a printhead which includes vertical columns of ink-jet nozzles. The printhead is scanned back and forth across a sheet of material to be printed with ink drops being ejected from the nozzles during the scans and the sheet being moved along a sheet path, perpendicular to the scan path, between scans of the printhead. This printhead scanning operation facilitates the adjustment of horizontal dot placement which is needed for printing within different site sizes on different sizes of sheet material. For example, 81/2 inch by 11 inch sheet material, usually having a 1/4 inch margin on each side of the sheet, is commonly used in the United States. However, other sheet sizes having other margins are also used and are often more common in other countries. A4 sheets, 21.0 cm. by 29.7 cm., are very common throughout the world and use a smaller margin than 81/2 inch by 11 inch sheets.
Printing within different site sizes, to accommodate differing margins or for other applications, is easily performed using a scanning printhead. The printhead simply deposits ink as it passes over the required printing locations of the sheets. Scanning printheads also simplify the alignment of black ink and color inks when black and color inks are ejected from two different sets of nozzles which are not necessarily consistently mechanically aligned with respect to one another. Thus, the black nozzles can be activated when they are over the appropriate sheet locations and the color nozzles can be activated when they are over appropriate sheet locations once the actual mechanical alignment between the black and color nozzles is determined and used to control the nozzles.
To increase the throughput of an ink-jet printer, page wide print arrays have been used. Such print arrays require substantially more nozzles than commonly used scanning printheads. For example, an 8 inch wide 300 dpi ink-jet printer requires 2400 nozzles for printing black (k). For color printing, separate print arrays are required for each of the colors, i.e., cyan (c), magenta (m) and yellow (y). Problems regarding the construction of page wide print arrays have been addressed in the prior art. See, for example, U.S. Pat. No. 5,440,332 and U.S. Pat. No. 5,469,199 which disclose page wide printhead structures.
In ink-jet printers having one or more page wide printheads, the printhead or printheads must be fixed within a printer with respect to the path which the print medium follows. This raises a problem with regard to precision placement of one or more page wide printheads within an ink-jet printer. Clearly, precision placement of printheads within printers can be accomplished; however, such precision placement adds substantially to the time and cost of manufacturing so that printers requiring precision page wide printhead placement are not commercially viable.
It is desired to reduce the cost of manufacturing ink-jet printers including page wide printheads by eliminating the need for precision placement of the page wide printheads within printers. Preferably, new ink-jet printers using one or more page wide printheads and methods of making the printers would require little, if any, additional hardware for eliminating the precision placement of the page wide printheads and, more preferably, would require no hardware but utilize available software capacity of the printers.